Car Stalls suddenly on LPG. Starts again straight away.
Hi Everyone,
I've had a really annoying prolem with my VT which started not long after I had the LPG system fitted. The car will usually start OK, and I can drive off, but get say 100m down the road and it just goes dead. No cough and splutter, just stalls. If I knock it into neutral and turn the ignition to start, it will normally start and off I go again. This can sometimes happen a couple of times. I have been trying for ages to identify what might triger it but I am still unsure. It seems to only happen when the engine is cold, but is usually worse if it is a hot day. I was suspecting that a faulty valve in my ac ducting might have been resposible. My car does the really annoying thing where I give a bit of throttle and the AC starts blowing on the windscreen instead of towards me, untill I back off the throttle. I thought this sudden surge/drop in manifold vacuum might have been doing something funny, but I'm not so sure after finding it still stalled with the AC turned off. Definitley seems to happen more under heavy acceleratiopn, or if you go from heavy acceleration to backed off straight away, like stopping at an intersection half way up a steep hill.
The car was back at the LPG installers constantly, and it did fault for them, but they have no idea why. checked the install multiple times and cannot work it out.
It is now at the point where I will probly just get rid of the car because my wife just finds it too unreliable to drive on LPG. IT DOESN'T STALL ON PETROL!!
If anyone has any experiences/tips/ or advice it would be greatly appreciated.
Ben.
I guess this one is a mystery to everyone then?
GRA = REAL HP
what system has been installed and by who ?
Hi strgas. Im not sure what brand the system is. Where is the best place to look to find out? I can tell you the tank is a Manchester tank, but i don't know about the rest of the system. It was installed by Thomas Jag and Mech. in Newcastle.
Ben.
GRA = REAL HP
can you put a pic of the under bonnet up.
yeah, i can. Will duck out and take one now
Here are a few pics of the gas system. The only branding I could see was LONGAS?
Ben.
GRA = REAL HP
ok its a simple ring mixer setup with maybe a stefanalli processor or emmegas , is there a hose running from the rear of the convertor to the dirty side of the air box for ram pressure , cant quite see one in the pic's , It maybe running lean on deccel and stalling out due to lack of balance line from the airbox or simply the mixture setting is to lean at idle ?
Yeah, it's got a hose (about 12mm ID) running all the way up to the duct at the front of the bonnet and is plumbed in just insite the opening to the duct. I am just about to have it serviced by Unique Auto Gas up here, so maybe it is worth getting them to check this out, or is there a way I can adjust it myself untill it gets serviced? Lean on deccel. sounds about right.
Ben.
GRA = REAL HP
you can adjust the mixtures using a mutli meter and reading the 02 sensor output , on the convertor there should be two points of adjustment one is idle screw and the other sensitivity adjustment . with the engine running auto in gear if auto if manual just A/C on handbrake on chock under wheel adjust the idle screw till you see a voltage reading between 500 - 600 mil volts.
Thanks strgas. Will try that in the morning! Just happen to have a multimeter in the shed! (I'm an electronics tech by trade, lol)
Always nice to get helpful advice!
GRA = REAL HP
no problem if its still stalling try drilling a 3mm hole in the back of the elbow in the convertor where the balance is fitted to lower the back pressure it maybe running to rich on deccel to . How much did you pay for the install ?
From memory it was $1800. About $400 out of pocket after the rebate. The installer lives next door to my mate, but he was pretty new to it all i think.
I had trouble whith my car stalling on gas when it was cold. it would do it just as i started to put my foot down i adjusted the idle speed up a little which seems to have fixed the problem well enuff. just an idea to try till you get it seen by someone.
Hmmm, still havent had a chance to look at it. My wife has had the car whenever I've had time to check it out. Maybe this weekend I will get time. Will post the results
Checked the O2 sensor today. It was reading 320mV while idling in gear. I've adjusted the idle mixture till it came up to 610mV. Will see how it goes over the next week.
Thanks for the help Strgas and Shane.
seems to be running ok so far. My wife was impressd that it didn't stall on her this morning. Will keep an eye on it and see how it goes i guess.
So far so good. Hasn't stalled since I adjusted the idle mixture.
Thanks.
LPG converter Balance hose\pipe incorrectly installed casing stall, stalls, stalling
hi there, the fix is easy. the balance hose that is coming off the back of the converter has been installed incorrectly.
It should not go all the way through the air box and then up the snorkel and stop around the opening of the snorkel. The hose will not balance the ram air pressure when installed like this which is a common installers mistake!!!.............. UNBELIEVABLE!!!!!!!!!!!!!!!!!
The simple fix is unclip the lid on your filter box, take out the air filter, and you should now see the hose going straight through your air box.
cut the hose with something suitable like a stanley knife (BE VERY CAREFUL) so only about 1 inch of hose is sticking out in your airbox and simply pull the rest of the hose out of the air box and snorkel and do what ever you want with it, just get it out!
You should only use the type of air filter that it was tuned to when you got the conversion done. for example if you got your LPG conversion tuned with a standard air filter, installing a high flow air filter will put the mixture out of whack.
your problem is an easy fix. the balance line was way too long for starters, and in a stupid place where it could not balance out the air pressure that your mixer was getting from the ram flow.
If you do what I say, you will be fine.
Balance line should always be as short as possible, and installed from the back of the converter running into your air box under the air filter known as the dirty side, and should only go into the filter box around one inch, and should also be pointing towards the airflow coming in to the air box. in a vt commodore scenario the hose should enter from the back of the box and point straight forward towards the headlight in direction.
The air box will provide you with the exact pressure it needs to keep the mixture happy.
sticking out the snorkel or even sitting a little inside is stupid and useless! there is no way it can get the correct pressure and your car will always lean out and stall under certain circumstances and coditions.
very dangerous when going down steep hills and you are on the brakes and stall......amonst other bad situations.
If worse came to worse you could even take off the cold air intake snorkel completely and remove the balance pipe off the converter completely, but DO NOT block off the hose connector that the balance pipe\hose was connected to on the converter, just leave it open with no hose attached.
All you would be doing is instead of getting cool air from the front of the car you would be using air that is in the engine bay just like the good old days with older cars. just dont block the opening that is left on the air box from where the snorkel used to be as that is where your engine will be getting its air from, and the converter should work quite well with no balance pipe\hose at all. just remember to not block off the fitting where the hose used to slip on to on the converter.
This second fix is for extreme troublesome situations only. My first fix should be fine.
at the end of the day, my first initial fix should work fine in 99.9% of cases like this one using the balace pipe just 1 inch inside the air box under the air filter being the dirtier side, and you can keep your cold air intake snorkel and be happy and safe and keep your car!!!!!!!
You are not on your own! this is way more common than you think!
All I can say is installers should know better.....they could kill somebody!!!!!!!!!!
this should sort out your problem berlinaben and anybody else with this same issue.
CHEEEEEEERS EVERYONE!
Hey good write-up mate, having issues stalling on gas with my vt series 2 berlina. With reguards to the balance hose going straight through the airbox; mine doesnt do that. the hose goes from the back of the convertor straight past the airbox and enters the box end of the snorkel with a 20mm brass elbow inside the snorkel. the brass elbow fitting is only lose, and im pretty sure the elbow was inverted so the open end was facing back toward the filter and not toward intake, would this have any dramatic effect on idling. it idles terribly and stalls straight after starting when cold (sometimes when hot)Originally Posted by mateyVTII
Thanks- Dan.
it's happened twice to my newly installed LPG the first time i heard a strange click and thought nothing of it and like you 100 m later the car stops and i'm able to start it straight away
2nd time same thing but this time i noticed the the trac light was out leading me to think that some safety solenoid is tripping
i would for check an earth problem
Yeah interesting thought. Seems my problem only exists on startup and at idle though. I have no such problems of stalling when driving, thanks anyway. ps i dont have trac ctrl.
Cheers, Dan
that's the 2 times it happened after starting car
when i first had it installed i had to take it back to get the switch over time adjusted from petrol to gas as it was at times hard start it runs perfectly now
just a thought
Oska That sounds more like it now actually. I think ill look further into getting the time extended that it takes to switch to gas (hopefully its not a hard set parameter on my system). Might also invest in a multimeter that has a millivolt scale to read the 02 sensor's output voltage at idle. might richen it up a tad.Thanks- Dan.
hey mate this could be a stupid answer but i didn't see you discuss anywhere the turn over from petrol to gas.
on cold mornings if i start my car in the morning for the first time that day, my car takes a minute or so to change from petrol to gas (lights on guage just flash until it clicks over) and sometimes it stalls when it changes over. I just run on petrol for the first few minutes then press the change button, and it swaps over straight away with no problems!
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